Hi all !. I have come to the time when I must bite the bullet and upgrade my now dying old Strobe. I have looked at the specs of the two leading options, but would like to hear from anyone who has experience of either / Both of these. What do I get for the extra money from the 580EX. That I won't from the MUCH cheaper EF 500 DG Super?. Is it just the CANON Badge. Or are there real benifits to either one..? Thanks... Tim H.